This invention relates generally to a fiber reinforced matrix for a wind turbine rotor blade, and more particularly to a wind turbine rotor blade including such a fiber reinforced matrix.
Wind turbine blades are typically made by means of two blade shell halves of fiber reinforced polymer. When molded the two halves are glued together along the edges and via bracings, which prior thereto have been glued to the inner face of one of the blade shell halves. The other blade shell half is then arranged on top of the bracings and glued thereto and along the edges.
The blade shell halves per se are typically made by vacuum infusion, in which evenly distributed fibers, rovings, which are fiber bundles, bands of rovings or mats, which may be felt mats of single-fibers or woven mats of fiber rovings, are layered in a mold part and covered by a vacuum bag. By creating vacuum in the cavity between an inner face of the mould part and the vacuum bag resin is sucked into and fills the cavity containing the fiber material. In order to obtain the optimum distribution of resin, so-called distribution layers and distribution channels are often used between the vacuum bag and the fiber material.
The matrix material used, i.e. a polymer, is typically polyester or epoxy, and the fiber reinforcement is usually based on fiber glass. It is, however, also known to use carbon fibers which are stiffer than glass fibers, but have a smaller elongation at breakage than glass fibers. Carbon fibers are, however, encumbered by the drawback of being significantly more expensive than glass fibers, which is one of the reasons why wind turbine blades of carbon fiber-reinforced polymer are not widely used.